init parses *.rc files from APEXes

Init now parses *.rc files from the APEXs when the apexd notifies the
mount event via apexd.status sysprop.

Bug: 117403679
Test: m apex.test; adb root; adb push <builtfile> /data/apex; adb reboot
adb root; adb shell setprop ctl.start apex.test; dmesg shows that init
tries to start the service which doesn't exist.

[   47.979657] init: Could not ctl.start for 'apex.test': Cannot find '/apex/com.android.example.apex/bin/test': No such file or directory

Change-Id: I3f12355346eeb212eca4de85b6b73257283fa054